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lbbio113 A few of this week’s topics What does it mean to be alive? Living things – life’s diversity The scientific method

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lbbio113

A few of this week’s topics

What does it mean to be alive?

Living things – life’s diversity

The scientific method

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Biology - study of life

All living things:

1. sense and respond to environment

2. capture and use energy

Metabolism = all the chemical reactions in a cell

Homeostasis = maintain internal operating conditions

within a range

3. reproduce, develop, grow

New cells only arise from previous cells

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4. are composed of at least one cell Some are unicellular

Some are multicellular

5. contain DNA Genes provide the instructions for the cell

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Genus and species

Binomial nomenclature

every living organism has two names which represent the genus and species

Felis domesticus F. domesticus

Canus familiaris

Mus musculus

R. rattus

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Life’s diversity

•2 million species have been described

•could be over 15 million species

•Living things are classified = Taxonomy

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No nucleus in cell Presence of nucleus in cell

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Eukarya Kingdom Animalia 3 characteristics?

motile, multicellular,

consumers

What IS this??

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Example of an animal useful to humans

Diabetes drug from venom/saliva

Gila monster (lizard)

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Plants – characteristics?

Multicellular

Photosynthesis

light

CO2 + H20 ------> O2 + starchSunlight is ultimate energy source for life – why?

Plants are producers

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Example of a plant useful to humans: Aloe

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Penicillin antibiotic

From bread mold

Revolutionized medicine

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Fig. 1.7 Euglena

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Domain Bacteria

3.5 billion years old

Prokaryotic cells

No nucleus

Single-celledintestine

plant

roots

On octopus mouth

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Domain Archaea

Methanosarcina mazei makes

methane from acetate

Fig. 1.5

“Chance favors the prepared mind” Louis Pasteur

SCIENCE Science - a process of discovery

objective

explain world using natural

processes

fish dead

because there

was a curse on it

fish dead

because there’s

no food in its

tank

Why is the fish dead?

Scientific method

I. OBSERVATION

2. HYPOTHESIS

educated guess

comes before the experiment

must be testable and falsifiable

Hypothesis = “educated” guess

Hypothesis must be Testable

Zinc lozenges ward off the common cold

Colds are disturbances in psychic energy

Meditation improves the immune system

Hypothesis – educated guess

Theory – supported by all data, a unifying

concept

Theory of gravity

Round earth

Mars year = 687 earth days Mercury = 87.8 earth days

The Experimental Method1. Control group = often a “no treatment” group

2. Experimental groups

EXPERIMENTAL VARIABLE (compare

control and experimental groups, what

is different)?

3. controlled variables

keep constant to insure only one experimental

variable per experiment

4. Measurement

Length, weight, count, etc…

Results = data obtained and analyzed

Never ignore data and stay away from

preconceived ideas

minimize bias

Placebo

Double blind studies

Placebo effect

The placebo effect is the observable, or

felt improvement in health not attributable

to treatment.

“Patients suffering pain after wisdom-tooth

extraction got just as much relief from a fake

application of ultrasound as from a real one, so

long as both patient and therapist thought the

machine was on”

The Placebo Prescription" by Margaret Talbot, New York Times Magazine, January 9, 2000).*

Evolution

Change through time

Change over time

“all organisms present of Earth today are

descendents of a single common ancestor

and all organisms represent the product of

millions of years of evolution”

Also known as common descent

Species

Group that can interbreed

Microevolution

Change within a species or population over

time

Speciation

New species arise from ancestral species

What is a Species?

One species is reproductively isolated from other

species.

Shares gene pool

HobbsMale lion female

tiger male ligers are

sterile, female ligers

are fertile

Female horse X male donkey horse X zebra False killer whale X bottle nose dolphin

Mandarin orange X pummelo

Fig. 16.3. All humans share a common ancestor

Horses have undergone much speciation

Sharks have changed very little in 40

million years

Natural Selection

How do we know what happened a long

time ago (geological time)?

250 mya Pangaea – continents came together

dramatic environmental change

mass extinction

Fig 16.13

Geological Time Scale

Age of Earth:

When living organisms first appeared:

Humans have been on Earth for 0.04% of the history of life

She: wore thick glasses and had brown hair in

grade school, she had laser eye surgery and dyed

her hair blond

He: was a “98 pound weakling” before body

building

They have a boy, what will he inherit?

No inheritance of acquired characteristics,

use and disuse of a structure does not lead

to inherited change

Fig14.8

Natural selection

versus acquired

characteristics

Natural Selection and common

descent (1859) ~evolution

Charles Darwin T.H. Huxley

HMS Beagle

Galapagos Islands

Volcanic islands off the coast of Ecuador that contain

unique species of plants and animals

Tortoise marine iguana

1836

Galapagos finches

Video

iguana

ala

Adaptive radiation Fig. 16.9

FINCHES HAVE ADAPTED TO ENVIRONMENTS

Fig. 14.6

Diet of seeds

Beak to catch insects

Probes cacti for nectar

All descended from a single ancestral species

Natural Selection – how does it

work?

1. Random variationA. All populations of organisms vary randomly

Variations are NOT imperfections but a normal aspect of species

B. Variation occurs due to mutation and

sexual reproduction

mutation = heritable change in DNA

DNA also rearranges during formation of sperm and egg

C. Variation inherited from parent to offspring

A few are harmful mutations :

hemophilia

A few are positive mutations :

beneficial (longer neck in giraffe)

4 million in 11 generations (800 years) ! Which survive??

3. “Survival of the fittest”= The most “fit”, or adapted organisms

survive and pass their genes on

Fitness is determined by the environment

Fitness = reproductive success

THIS IS NATURAL

SELECTION

Another adaptation to

avoid predation

Fig 14.9

Brazilian alligator bug

Examples of adaptations (increase

fitness)

4. Descent with modification

Offspring inherit traits of parents =

Descent with modification =

Evolution

Natural selection results in adaptive traits

increasingly represented in each

succeeding generation

pg. 223

May take a lot of time for change to be

obvious and lead to a new species

speciation

Ancestral species give rise to new species

The most well adapted (most fit) organisms survive to reproduce

Traits that increase fitness are adaptations

Western diamond back rattlesnake

Artificial Selection – breeding of domesticated

animals and plants by humans, this is NOT natural

selection

Cows, corn, dogs

Bulldog

Evolution

change through time

The Grand Canyon was not

produced by a catastrophe

Arizona

2. Fossils, pg. 224 History of life recorded by remains of past

Living matter buried in volcanic ash or sediments for >10,000 years

mineralized + pressure = hard

Types

Impression

Bones, teeth

Amber

Petrified wood (organic materials replaced with minerals)

Mosasaurus

Tooth 50 ft. 70 mya

Incomplete record

no preservation of soft organisms or parts

Jellyfish, hearts, brains

Why is the fossil record

incomplete? 75% of the earth is ocean

Many destroyed by weather

Fossils don’t always form A small number are buried in the right way (fast) to prevent decomposition

Cant dig up entire earth, many still buried

No soft parts

Texas New Jersey

Impressions

http://digsfossils.com/f

ossils/footprints_main.

html

Fig 16.10 Only the hard parts remain after fossilization

process

99% of species once alive are extinct

~ 2 billion total

Stratification: simple=oldest= deepestSuccession of life

forms

Hadrosaurus, Haddonfield, NJ 1858

The NJ State Dinosaur

Coelacanths!

1938, a Coelacanth was caught at the mouth of the Chalumna River on the east coast of South Africa.

Coelacanth fossilized in rock dated 70 million years ago

Fossils found a few years ago

A bison-size rodent, Phoberomys pattersoni, grazed on aquatic

grasses and roamed the riverbanks of ancient Venezuela about

8 million years ago.

Glyptodon and modern

armadillo

Fig 14.4

Kutchicetus 40 mya

A famous hominid fossil

1974, Hadar, Ethiopia.

Lucy – (Australopithecus afarensis)

East Africa ... 3.2 million years ago

Pelvis - walked upright on two legs.

Arms – good climber

Lucy

300 individuals found

3 feet 8 inches tall

More ape-like than human

archaeopteryx- a

dinosaur/bird link

Late Jurassic period, and specimens have been found in limestone deposits in Bavaria, West Germany. The first specimen was discovered in 1861, and since then six skeletons have been found.

3. transitional forms

Fig.

14.11

Red = reptile Green = bird

5. Anatomy

Homologous structures

Share a common

evolutionary history but

may be used for

different functions

Fig. 14.14

Analogous structures

similar function but no shared evolutionary

history

Vestigial structures

Function lost during

evolution, no longer

needed

human appendix, whale leg

bones, snake leg bones

This is your appendix………..

Pre- and post-evolutionary theory,

page 218

Mammals- what makes a

mammal a mammal??

Marsupials – development in

pouch

Placental mammals

Born more fully developed

Placenta in uterus

Ex. Bat, polar bear, human, whale, cow,

armadillo……..